Conventionally, in an electric vehicle or the like, a plurality of batteries connected in series is used as a power source having high voltage or high power. Connecting plates made of a synthetic resin, which is coupled to each of the batteries, has a cut-away portion or a flexible portion therebetween. In such a way, since the connecting plates have a contractility, the connecting plates can absorb the dispersion of the sizes between battery terminals by manufacturing allowance (for example, referring to Patent Literature 1 or 2.